The present invention relates generally to personal flotation devices. More particularly, the present invention relates to a method for constructing or fabricating a personal flotation device having a flotation foam core.
Personal flotation devices (PFD""s) and life jackets are commonly used in recreational water sports as a safety apparatus to prevent accidental death due to drowning. This is primarily achieved through the use of buoyant materials in the PFD which help support the body near the water surface, particularly the head and face of the wearer, so they may float on or near the surface with little or no effort. FIGS. 1 and 2 show front and back views of a typical PFD. PFD 20 has the form of a vest with openings for a wearer""s neck, arms and waist. A strap 22 with a locking buckle allows the wearer to secure the vest around their torso.
Many users tend to remove the PFD during their activity, or abstain from wearing the PFD altogether because they find the PFD uncomfortable. This discomfort occurs mainly due to the nature of the flotation foam within the PFD. The flotation foam must meet safety regulations such as the U.S. Coast Guard Regulations and the Canadian General Standard Board (CGSB), while preferably minimizing bulk to allow sufficient freedom of arm and shoulder mobility demanded by recreational water sports. Hard foams are typically used due to their low cost and high buoyancy characteristics. Examples of hard foams include closed cell polyethylene and polypropylene foams. One type of closed cell polypropylene foam is an FF2C foam. Hard foam does not conform well to a person""s body, and is therefore found to be uncomfortable during use. Accordingly, there is a concern that people are not wearing their PFD""s due to the discomfort experienced, and hence have an increased risk of mortality.
Much of the comfort of a PFD is derived from the softness, shape and placement of its flotation foam. The common method for construction of PFD""s with such foam is described below with reference to FIGS. 3 through 5. FIGS. 3 through 5 illustrate cross-sectional views of the PFD along line Axe2x80x94A in FIG. 1 or line Bxe2x80x94B in FIG. 2 at various stages of construction. The PED can be constructed of multiple small pockets to increase its flexibility, and accordingly, the cross-sectional images can be representative of a single pocket.
As shown in FIG. 3, the construction of typical PFD""s begins by placing a shell material 24 back-to-back with a liner material 26 such that the outside surfaces are facing each other as shown in FIG. 3. The edges of the shell 24 and liner 26 are sewn together as illustrated by stitches 28 to form a pocket. In FIG. 4, the shell 24 and liner 26 are turned inside out such that their respective outside surfaces are facing outwards and the stitching is now on the inside of the pocket. Once the pocket has been turned inside out, it can be stuffed with flotation foam. FIG. 5 illustrates the pocket stuffed with different layers of foam. The layers 30 and 32 are typically hard foam, but can also be soft foam, arranged in various combinations. Examples of soft foams are those commonly sold under the trademarks xe2x80x9cENSOLITExe2x80x9d and xe2x80x9cAIREXxe2x80x9d. FIG. 6 illustrates an alternative stuffing of a single piece of hard or soft foam 34 with tapered edges to increase comfort to the wearer.
Unfortunately, the hard foam 32 in FIG. 5 has edges that are a source of discomfort. In the alternative stuffing of FIG. 6, the hard or soft foam 34 with tapered edges may increase the cost and time for manufacturing the PFD because the edges must be formed, for example, through cutting the hard foam 34 prior to its insertion into the pocket. Consequently, there is wasted foam as a result of the cutting process.
It is, therefore, desirable to provide a PFD that is comfortable to wear while remaining inexpensive to produce, for augmenting PFD use.
It is an object of the present invention to obviate or mitigate at least one disadvantage of previous personal flotation devices and methods for constructing personal flotation devices. It is a particular object to provide a low cost, comfortable personal flotation device.
In a first aspect, the present invention provides a personal flotation device. The personal flotation devices includes at least one pocket having two material layers directly fastened to each other, at least one soft foam layer fastened to at least one of the two material layers, and flotation foam positioned between the soft foam layer and the other of the two material layers.
In farther embodiments of the first aspect, the two material layers are fastened to each other at their edges and the at least one soft foam layer is fastened to one of the two material layers at its edges. Furthermore, the two material layers include a lining and a shell and the at least one soft foam layer is fastened to the shell.
In yet another embodiment of the first aspect, the at least one pocket is an inverted pocket, and the flotation foam includes hard foam or layers of hard foam and soft foam. In further aspects of the present embodiment, the at least one soft foam layer is sewn, glued, taped or heat laminated to one of the two material layers.
In other embodiments of the first aspect, one soft foam layer is fastened to each of the two material layers, and the at least one soft foam layer and the at least one of the two material layers have a convex shape.
In another aspect, the present invention provides a method for manufacturing a personal flotation device. The method includes the steps of fastening a first material to a second material at their edges to form an open pocket and fastening a soft foam layer to the exterior of the first material by its edges. In subsequent steps, the open pocket is turned to form an inverted pocket, a flotation foam is inserted into the inverted pocket, and open ends of the inverted pocket are fastened together. In a further embodiment of the present aspect, the soft foam layer, the shell and the liner are simultaneously sewn together at their edges.
In further alternate embodiments of the present aspect, the soft foam layer is sewn, glued, taped or heat laminated to the exterior of the first material.
Other aspects and features of the present invention will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures.